Primer Pump problem.

alang · Post by **alang** » Wed Mar 25, 2009 4:26 pm

Hi folks,

I went out to do some harrowing, a couple of days after posting my earlier “Drug Rehab - it's never too late” bulletin, and after about 45 minutes, when I asked for a little effort to climb a steep slope, the engine coughed and died. The fuel system was full of air - she ran again after bleeding but cut out again and again that morning. I was happy no air was getting in and suspected fuel starvation. I called the supplier of the new primer pump who advised removing the restriction pin/clip to allow the stop tap to open further (4-5 turns instead of the normal 2).

Next day I followed the same start routine of one push on the primer to wet the heater, then 30'ish seconds of heat, then two pushes on the primer (with heat) - but the engine could not turnover because, as it turned out, too much diesel had been pumped into the cylinder and it couldn't displace it. I removed the heater and allowed the diesel to drain/evaporate overnight.

The following day, having replaced the heater, I opened the fuel tap 2 turns and started her using my proven routine - once running I turned off the manifold stop tap and opened the fuel tap another 2 turns. I have done two days work this way and so far no further problems.

I wondered if my experience is unusual or not?

Cheers
Alan

terry274 · Post by **terry274** » Wed Mar 25, 2009 4:50 pm

I replaced the primer on my Super Dexta (last month) and I am having trouble with the tap leaking into the heater and getting into the crankcase. This seems to be a common problem with the replacement fuel taps. I am looking for a fuel shut off valve to go in the 3/16'' heater fuel supply line. My post "oil level in crankcase" about three posts down describes what has happened with my tractor. Also, there is some mention of this in the post "oil in exhaust" right below your post.
Let us know how you work this out. I am not happy with the quality of the replacement fuel tap. Spent a lot of money, time and work to change it and now this!
Terry

terry274 · Post by **terry274** » Wed Mar 25, 2009 4:54 pm

I just reread your post and saw

once running I turned off the manifold stop tap

What type of stop tap do you have? Did you add it? Will you post a picture, this is just what I need.
Thanks, Terry

alang · Post by **alang** » Wed Mar 25, 2009 6:03 pm

Terry,

I purchased a full set of parts which contained 1) The primer pump. 2) The pump to manifold pipe. 3) The manifold tap.

See this page and look for items 7213 and 7212
<http://www.agrilineproducts.com/dexta_cart.htm>

They told me it's important to stop the possibility of fuel getting into the manifold once started and also air getting from the manifold into the fuel system. I should say that I had to adjust the manifold tap as the shutter was the wrong way round and it hit the manifold when turned on. Not a problem to do.

One other warning. Manifolds are as rare as rocking horse sh*t so I fixed my tap in with a Locktite compound and ptfe tape. There can be a risk of over tightening and stripping the soft aluminum thread.

Hope this helps (by the way I normally use a Mac but have just bought a Linux based Acer Aspire One)

Cheers
Alan

dexta4 · Post by **dexta4** » Wed Mar 25, 2009 8:34 pm

the manifold taps were put on from new on later dextas..

terry274 · Post by **terry274** » Wed Mar 25, 2009 8:41 pm

I am using Arch Linux and really like it. I recently switched from Gentoo. I have also used Red Hat (a long time ago) and built Linux from scratch.
What version of Linux does your Acer run?
Terry

alang · Post by **alang** » Wed Mar 25, 2009 10:11 pm

Terry,
The Acer is a notebook and great for the internet, it runs Linpus Linux Lite v1.0.9.E. Sorry to say I am not up on computers - I just dislike PC's and Microsoft which were compulsory issue when I worked. In truth I'm sold on Mac's because they are so easy to operate and joined up.
Getting back to the Dexta problem... Dexta4 your right, it would be interesting to know if it's possible to run with a primer fitted but without the manifold tap. Your Dextas must cover the period before and after the tap was fitted as standard, how are you configured?
Cheers
Alan

JohnG · Post by **JohnG** » Thu Mar 26, 2009 12:31 pm

Hi Terry and Alan

Thought I would add my next post here rather than on my thread ‘Oil in Exhaust’. My Dexta is a ‘59 without the later inline stop tap.

Following my extremely smokey start up a couple of weeks ago after the installation of the new primer pump, I decided to remove the jet from the air manifold, and with the pipe connection nice and tight (so that this was not leaking), secured a small polythene end over the end to see what drained out.

Clearly the valve in the jet was not holding back the flow, as about 15ml or so of fuel had drained into the bag over about a week.

Last weekend I fitted a new combined jet/stop tap. I fired the Dexta up this morning having first checked that the heater plug was dry and it all looked pretty normal and started ok.

I did however remove the new jet from the manifold just to see if this would allow fuel to bypass. With the stop tap open, the new jet dribbled fuel. Two questions - is the new jet actually a valve or just a hole with a tap, or are the new primer pumps over pressurising the pipe? Or is this all just normal?

Also, finally, could I have done any damage whan I initially fired up with the excess diesel in the manifold?

Thanks

John

alang · Post by **alang** » Thu Mar 26, 2009 1:51 pm

John,

The supplier of my primer kit has been helpful, but the whole kit cost me £75 (85 if the heater switch is included) and that's a lot to pay for the amount of fiddling I've had to do.

I think your description of 'just a hole with a tap' is right, it doesn't seem to atomise the diesel. My problem was that the pump when opened beyond it's 2 turn limit basically delivered enough neat diesel into a cylinder to stop it turning over. I think the pressure of delivery is dependent on how strong your left thumb is - but quantity is a function of the primer on/off screw.

Not sure about damage but since the adjustments I'm working great. Have you read the earlier post with Gerald’s starting instructions from his reply to Tomsdexta’s topic “Hard Starting” posted Dec 07, 2008. I found this very helpful especially the bit about wetting the heater.

Cheers
Alan

Tubal Cain · Post by **Tubal Cain** » Thu Mar 26, 2009 6:04 pm

I am almost certain that a spring loaded valve was fitted originally to prevent fuel seeping into the manifold. There is a comment somewhere concerning the fitting of a brass shutoff cock in the priming line, these are available from Agriline.

The amount of fuel delivered by the priming pump per stroke is dependent on the displacement of the pump, which is a product of the plunger diameter multiplied by its stroke and I wouldn't have thought that it delivered enough to flood the engine. If this has happened I would suggest that the fuel is draining from the tank into the manifold. Check to see if a spring loaded valve is fitted.

On the Super Dextas there is a cold start button fitted on the fuel pump, it is located on the end of the shaft on which the stop lever turns. With the throttle open this button can be pushed in and it will lock in the excess fuel position until the engine starts to run. Normally in the UK the engine will start with the aid of the cold start without the need for preheating.

You can test whether the tap/primer are leaking by disconnecting the primer line and observing whether or not fuel flows with the tap open, if it does I would be inclined to return the assembly as it isn't fit for service.

Some years ago I bought a fuel tap primer assy from Vintage Tractor Spares Which cost close to £100.00. Some time later I saw a similar item being sold by Patrick Edwards for about £40.00, when I queried the price difference it was suggested that the primer I had bought was made in this country whilst the cheaper item had been made abroad.

Gerald

dexta4 · Post by **dexta4** » Thu Mar 26, 2009 9:07 pm

i run original primer pumps hooked up to the later type heater plug with its own diesel feed,i leave my fuel tap on 365 days a year and no problems at all!! some people tell you that you cant get a later type heater plug for the dexta and you have to get one for a mf 35 and have the dexta manifold rethreaded! but if you get one for a fergie t20 diesel it goes straight in.. the earlier dextas do have a spring loaded valve in the manifold but these can let diesel past thats why they swapped to the tap.

terry274 · Post by **terry274** » Thu Mar 26, 2009 11:47 pm

dexta4

but if you get one for a fergie t20 diesel it goes straight in.

Can you give me more information about this? A part number?
Thanks, Terry

dexta4 · Post by **dexta4** » Fri Mar 27, 2009 6:32 pm

got mine from old 20 parts,the number stamped on them is either 11720 959 or H720 959 they look like this

diesel pipe screws on here ^^^^, when fitting you have take the inlet manifold off as the wire conector catches as you are screwing it in.

dexta61 · Post by **dexta61** » Sat Mar 28, 2009 9:20 am

I have bought a new heater from agrilineproduct see web site above. It fitted wel only you need to remove the the nut from the oil supply line to get it installed.

In my dexta the copper line to to manifold was cut and closed so I still have the nozzle, but it seem to be stuck, does any one know how this works? With blowing it with air it does not seem to open.

Also the new primer pump, which is also new, seems to pump very hard. any sugestions here as well?

alang · Post by **alang** » Sat Mar 28, 2009 9:44 am

Dexta61,
My experience is that the pump is best when hard to push. I agree it's difficult, if seated, to use your left hand finger or thumb to press the plunger. I disconnected the manifold end too see just how much diesel squirted out and was surprised that it took little pushing to deliver enough diesel. But I suppose 'enough' may be dependent on each tractors individual state of wear.
Cheers
Alan

Bensdexta · Post by **Bensdexta** » Sat Mar 28, 2009 10:14 am

By way of a reminder, Stefan made his own fuel tap that didn't leak, described in detail here:
http://www.fordson-dexta.de/501255978f1 ... index.html
I'm expect he would be happy to answer Q's about it.
All the best,
Ben

Tubal Cain · Post by **Tubal Cain** » Sat Mar 28, 2009 6:44 pm

The original valves fitted in the manifold had a ball which was held against the seat by a spring. Operating the priming pump would create sufficient pressure in the priming line to overcome the spring and allow the ball to lift off its seat allowing Diesel to flow into the manifold, as the pressure decayed the ball would then reseat and close off the flow of Diesel.

The orifice in the spring loaded valve is quite small so there will be some resistance to the flow as noticed when operating the priming pump.

Remember that when the engine is running a vacuum is created in the manifold which could cause fuel to flow from the tank into the manifold if the valve is defective or not present. Obviously a tap in the line will prevent this.

One other point, my 1959 Dexta has the original primer and heater still fitted. When I first bought it I inadvertently caused a minor explosion in the manifold whilst using the primer which resulted in oil being blown out of the air cleaner oil bath. You have been warned.

Gerald

alang · Post by **alang** » Sat Mar 28, 2009 8:28 pm

Gerald,
Just when I thought I had it sorted, you tell me I've fitted a bomb!
Still best to be warned - do you have an explanation for the explosion? And what do you think the odds of it happening again are?
Cheers
Alan

Tubal Cain · Post by **Tubal Cain** » Sun Mar 29, 2009 8:24 am

Alan,

I suspect that the minor explosion occurred because I pumped additional fuel into the manifold whilst the engine was stopped!

If the engine is turning over any flames or products of combustion due to Diesel coming into contact with the heater will be drawn into the cylinders. This has the effect of increasing the temperature in the cylinder of the cold engine thus assisting the atomised fuel to ignite which in turn causes the engine to run.

If the engine is stopped the increase in pressure due to the Diesel igniting takes the path of least resistance, which in this case is the seal in the air filter created by the oil in the bowl.

So I wouldn't describe it as a bomb as the worst scenario is for your bonnet to end up covered in dirty oil.

Gerald.

Raymondc71 · Post by **Raymondc71** » Wed Jan 06, 2010 11:34 pm

i had no primer on my dexta and got a new 1..i got a simle shut tap which screw into the manifold..this comes on a copper wire which brings the diesel from the primer to the manifold..i got it of DUNLOP TRACTOR SPARES...im 16 and have nearly restored the 1959 dexta..im justoverhauling the hydrualic system which is really quite simple..the lifts would lift but would not drop unless pressure was applied...i have cleaned the filters and inserted all the o rings and hopefullly it will work ok..the control lever was really loose and wasnt lining up with the pump so i have put in a new friction plate..ANY HELP mondocahill@live.ie

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